1. Field of the Invention
This invention relates to optical disk systems, and in particular to optical disk systems for playing back recorded presentations (e.g., viewing movies).
2. Description of the Related Art
Optical disks are recording media typically containing long strings of microscopic pits representing digitally encoded data. Each string of pits is called a "track". The tracks are formed end to end in a spiral pattern around the center of one or both major surfaces of the disk. Reflected laser light is used to "read" the data encoded in the pits. Common types of optical disks available today include compact disks (CDs), laser video disks, and digital versatile disks (DVDs). Various optical disk players are available which read data from optical disks.
The current DVD standard is a compromise format agreed upon by several major consumer electronic and entertainment companies. Under the current DVD standard, the capacity of a single side, single layer DVD with a diameter of 4.7 inches is 4.7 gigabytes, enough to store about 135 minutes of video data. This capacity is sufficient for about 95% of all full length movies. The current DVD standard also provides for up to eight different sound tracks in different languages, each with up to eight different audio channels to create a three-dimensional acoustic effect. In addition, up to 32 different sets of subtitles (i.e., translation text) may be stored on a DVD for display during playback.
Many users have favorite movie scenes, and like having the ability to view those scenes without having to view the entire movie. With a linear recording media like video tape, accessing a particular scene may involve determining the distance from the beginning of the tape to the start of the section of the tape where the scene is stored. The distance may be measure in inches, for example, and a counter having a visual display may be used to measure the length of tape passing between two rollers.
In order to view a particular favorite scene, a video tape system user may reset (i.e., "zero") the counter at the beginning the tape, allow the tape to advance to the beginning of the scene, then write down (i.e., record) the value displayed by the counter. In order to view the scene at a later date, the user may again reset the counter at the beginning of the tape, advance the tape at an accelerated rate (e.g. "fast forward" the tape) until the displayed value matches the recorded value, then replay the favorite scene.
A user's written record of counter values (i.e., list of indices) corresponding to beginnings of favorite scenes is subject to loss. In addition, the user must manually access the sections of recording media containing the favorite scenes. It would thus be beneficial to have an optical disk system which embodies a method for storing indices corresponding to selected portions of recorded presentations. The desired system would store the locations of the beginnings of the selected portions of the presentations (e.g., indices to favorite scenes) for multiple optical disks (e.g., DVDs). Further, the locations of the beginnings of the selected portions of the presentations would be accessible by a control mechanism of the optical disk system. The control mechanism would automatically access and begin playback at the selected portion of a particular presentation. Such a system would allow a user to conveniently keep a record of and access selected portions of multiple presentations (e.g., favorite scenes in several different movies).